The diurnal cycles of surface rainfall, population of precipitation systems, deep intense convection reaching near the tropopause, lightning flash counts, cold clouds, and vertical structure of precipitation are analyzed over the tropics, using 9 years of TRMM Precipitation Radar, Visible and Infrared Scanner, and Lightning Imaging Sensor measurements. The diurnal cycles over land include a late afternoon maximum of precipitation systems, with phase differences among cloud, precipitation, flash counts, and radar echo at different altitudes. Over ocean, the diurnal cycles are interpreted as having contributions from nocturnal precipitation systems and early afternoon showers. There are double peaks of radar reflectivity above 12 km near 0230 and 0530 local time over oceans. The oceanic clouds with infrared brightness temperature < 235 K have two peaks, one during the night and the other in early afternoon.